Lifting jack



I. V. K. HOTT Feb. 23, 1932.

LIF'IING JACK 3 shets-sheet Filed April l0, 1925 INVENTOR.

ATTORNEY Feb. 23, 1932. y|."v. K. HoTT 1,346,333

LIFTING JACK Filed April 10, 1925 3 Sheets-Sheet 2 /N VENTO/e [ONM/H077 BY C2 l L 6 ,//A TTORNE Y Feb. 23, 1932. 1, V; K. HQTT 1,846,333

LIFTING JACK Filed April 10, 1925 5 Sheets-Sheet 5 /NVENTR Jovi/44%?? BY s l A TTRNEY Patented Feb. 23, 1932 UNITED STATES PATENT OFFICE `IKJN V. K. HOTT, F DAYTON, OHIO, ASSIGNOR T0 THE JOYCE-CRIDLAND COMPANY, OF

DAYTON, OHIO, A CORPORATION OF OHIO LIFTING JACK Application led April 10, 1925. Serial No. 22,194.

rl`his invention relates to iifting jacks and more particularly to a lifting jack having a retarding device or brake which is actuated automatically by 'the tendency of the load to .move downward to retard that downward movement, and which may be manipulated so as to lower the load by the application of a small amount of power by the operator.

Une object of the invention is to provide a jack of this kind with improved means for actuating the brake mechanism to control the movement of the load.

il further object of the invention is to pro 1fide a jack of this kind with means which will operate automatically to checl the movement of the load and prevent the same from dropping under abnormal conditions.

fi further objectof the invention is to provide in such a lifting jacl; a bralre having cooperating friction surfaces of such a character as to provide a maximum of frictionai resistance tothe relative movement of the parts but which will not be marred or otherwise damaged by the relative movement of the surfaces under the weight of the load.

@ther objects of the invention will appear the device is described in detail.

in the accompanying drawings Fig. l is a side elevation, partly broken away, of a jat-lr embodying my invention; `F ig. 2 is a front elevation of the ack, partly in section, showing the operating' mechanism therefor; F 3 is a perspective view of the manually operated handle for lowering the load; Fig. l is a similar view showing the handle and its associated parts in an inverted position; lt1 ig. 5 is a face view of a modified form of clutch or brake member; Fig. 6 is a side elevation, partly in section, of the clutch member of Fig. Fig. 7 is a front elevation of another form of clutch member; and 8 is a side elevation, partly in section, of the clutch member shown in Fig. 7.

ln these drawings I have illustrated one embodiment of my invention and have shown the same in connection with a lifting ack of the type shown in, the application for patent filed by me January 21, 1925, Serial No. 3,741 patented December 20, 1927, as Patent No. 1,653,179, but it will be understood that this embodiment has been chosen for the purposes of illustration only and that the mechanism may take various forms and may be applied to jacks of various kinds.

As here shown the jack comprises a base l on which is mounted an upwardly extending housing or hollow standard 2 within which is provided a bearing for a lifting element or ram 3 which is `also hollow and is provided at its lower end with a nut 4 to receive a screw 5 which is rotatably mounted at its lower end on the base 1, all in a Well known manner. Rigidly secured to the shank of the screw 5 near the hase 1 is a `beveled gear 6 which meshes with a beveled pinion 7 rigidly secured to or formed integral with a shaft 8 which is ournaled in bearings 9 and 10 in the housing or standard 2 and in a third bearing 11 formed in a supplemental housing 12 which is secured to the side of the main housing or standard and which encloses the controlling mechanism. The beveled pinion is connected with a suitable operating device by means of which it may be rotated to rotate the screw 5 and elevate the lifting element. In the present jack reducing gearing is interposed between the operating device and the beveled pinion and to this end I have mounted on the shaft 8, within the housing 12, a gear 13 which meshes with a second gear 14 secured to a shaft 15 mounted in bearings 16 and'17. The outer end of the shaft projects beyond the outer wall of the housing 12 to receive the operating device. As here shown, the operating device is in the form of a lever socket 18 adapted to receive an operating lever and connected with the shaft 15 by the usual pawl and ratchet mechanism. The operating device forms no part of the present invention and it is not necessary that it be shown in detail.

The screw 5 is of the quick pitch type and will rotate under the weight of a load, when unrestrained. In order to control the rotation of the screw under the weight of the load I have secured to the shaft 15 aworm wheel 19 which meshes with a worm 2O mounted on a shaft 21 extending transversely to the shaft 15 and journaled in bearings 22 and 23 formed in the housing 12. The shaft 21 is capable of a slight longitudinal movement, as well as a rotatory movement, and has rigidly secured thereto a brake member 24, here s''bwn as a tapered friction member adapted to enter a tapered seat carried by the housing 12 and constituting a cooperating friction member. It is important that the surfaces of these cooperating friction members should be of such a character as to offer ahigh frictional resistance to the relative movement of the members and that they should also be of such a character that they will not be marred or otherwise injured by abrasions due to the relative movements of the twoV members under the weight of the load. I have therefore provided one of the friction members with a contact surface of fabric which has been treated to solidify the same. Preferably the fabric is impregnated with a plastic substance, molded to form and then treated to solidify the same. In the present construction a ring of this solidified fabric is seated in the housing 12 about the end of the shaft 21, as shown at 25, and has its inner surface flared inwardly to provide a tapered seat for the friction member 24, which is preferably of metal. rIhe friction member 25 is fitted snugly in an opening or recess in the housing and is retained therein by a pin 2G or other suitable fastening device. In order that the friction member 25 may be readily removed when worn the end of the housing is provided with openings 27 in line with the friction member and through which pins or other implements may be inserted to drive the frictionlmember out of its recess, after the pin 26 has been removed.

Obviously the solidified fabric surface may be applied to either the fixed friction member or the movable friction member and, in Figs. 5 and 5, I have shown it applied to the movable friction member. As there shown, the friction member comprises a sleeve or body portion 28 rigidly secured to the shaft 21 and having a radial flange 29 at its inner end. Mounted'on the sleeve 28 is a tapered body of solidified fabric 30 which is held in position thereon by a flat ring 31 extending about the body 28 at the outer end thereof and connected with the flange 29 by rivets or bolts 32. In Figs. 7 and 8, I have shown a similar construction in which I have substituted disks 33 which may be of the solidified fabric or of leather, or other suitable material, the clutch member being otherwise of the same construction as shown in Figs. 5 and 6.

The brake member 24 is rigidly secured to the shaft 21 so as to have both axial and rotatory movement therewith. The worm 2O is so mounted on the shaft that it may be caused to move axially therewith and to rotate therewith. In the present construction, however, it is loosely mounted on the shaft and is capable of a slight axial movement thereon with relation to the clutch member 24, the adjacent ends of the clutch member and the worm being provided with clutch faces, as shown at 34, which are brought into cooperative engagement by the end thrust exerted upon the worm by the worm wheel 19 during the downward movement of the load, thus causing the worm to be rigidly connected with the shaft and clutch member dur- When the ing this downward movement. worm wheel 19 is rotated by the screw 5 upon the downward movement of the load it will cause the worm to engage the clutch or brake member 24 and force the same into firm frictional contact with the cooperating brake member 25 and thus hold the worm wheel and screw against furthermovement. This holding device is constantly operative and will check the reverse movement of the load instantly between the successive operations of the operating lever on the shaft 15. When the worm wheel 19 is rotated in a forward direction by the rotation of the shaft 15 the end thrust imparted to the worm 20 will move the same inthe opposite direction and will release the same for rotation relatively to the clutch member, thus permitting the load to be elevated without affecting the brake mechanism, but as soon as the operation of the lifting mechanism is interrupted the weight of the load will impart a reverse movement to the worm wheel 19 which will cause the worm to be connected with the brake member 24 and that member to be rmly seated against its cooperating brake member, thereby checking the tendency of the load to move downwardly.

TWhen it is desired to lower the load a slight axial movement is imparted to the brake member 24 to relieve the pressure thereof on the coperating brake member 25, but its connection with the worm 2O is maintained so that the worm cannot be rotated with relation to the shaft 21 by the reverse movement of the worm wheel 19. This is accomplished by imparting axial movement to the shaft 21 and for this purpose I have mounted on that shaft a sleeve or hub member 35 which is capable'of rotatory and axial movement on the shaft and which is arranged to bear against the outer end of the bearing 23. This hub or sleeve is provided with a helical slot 36 through which extends a pin 37 rigidly mounted in the shaft 21. The arrangement of the slot 36 is such that when the sleeve is 34+? rotated in a direction to lower the load the inclined wall of the slot will act on the pin 37 to impart axial movement to the shaft 21 and thereby reduce the pressure of the brake member 24 on the brake member 25 sufficiently to permit the former to be rotated. Movement is imparted to the sleeve 35 by a handle or crank 38 which is preferably pivotally mounted thereon so that it may be folded into a position alongside of the shaft when not in tia use. The end ofthe housing 12 adjacentto the bearing 23 is provided witha projection or log 89 with which the handle will engage when in its folded position and thus positively loclr the hub or sleeve 35 against rotation7 the handle being retained in its folded or inoperative position by means of a plunger' 401, as described in the above mentioned application.

During the lifting operation and when the load is to be held in its elevated position the handle 38 is in its folded position engaging with the stop 39 so that the hub 35 thereof is positively locked against rotation and inasmuch as the movement of the shaft with relation to the hub is controlled by the pin 37 extending through the cam slot the shaft is also locked against rotation and the load is held against downward movement. The handle is preferably provided with a cam portion 43 which acts on the pin 37, when the handle is moved to its folded position to rotate the hub and thus cause the helical slot to act on the pin to move the hub outwardly and cause the pin to seat against the inner end of the slot. 1When the load is to be lowered the handle is moved to its operative position, thus releasing the pin, and the forward movement of the handle will first move the hub with relation to the pin so as to cause the inner end of the hub to Contact with the bearing 23 and this contact will be maintained during the normal lowering operation. The further movement of the handhI will rotate the hub with relation to the shaft in a forward direction so that the cam surface or wall of the slot will act on the pin 3T to impart a. slight axial movement to the shaft and the brake member 24, sutlicient to partially release the brake but not sufficient to release the load or permit the same to rotate the brake member 24. The continued rotation of the handle and the hub will cause the cam surface of the slot to act on the pin and shaft to rotate the shaft and the worm against the reduced resistance of the brake and permit the worm wheel to be rotated by the load or to force the load downwardly if the lifting screw is not rotated by the load.

lf. after the load has been started downward and the inertia overcome, the load tends to run down under its own weight so that the worm wheel 19 will rotate the worm 20, the

Aj shaft will run ahead of the hub and the movement of the pin 37 in the slot 36 will permit the end thrust on the worm to impart axial movement to the shaft and move the brake member 24 into lirmer engagement with the brake member 25, thereby checking the downward movement of the load. Consequently the load is under the positive control of the operator at all times and it can move downwardly only when the worm 20 is rotated by the handle 38. If this rotationis interrupted the brake will check the movement of the load.

I have also provided means for positively checking the downward movement of the load under abnormal conditions which would prevent the brake from functioning properly and which in the absence of some other controlling means might permit the load to run down without control by the operator. Such conditions'are improbable but might exist if the brake members become so worn or glazed as to not have sufficient frictional contact to control the moving load or if a foreign substance should enter the space between the two brake members and prevent the proper engagement of their contact surfaces. Under such circumstances, after the brake has been partially released and the load started downwardly, the worm and brake member 24 would tend to rotate under the influence of the load and to check this rotation and bring the load under control I have provided the hub 35 near its inner end with a tapered projection or cam 41 which is arranged to cooperate with a lug 42 rigidly secured to but spaced from the outer end of the bearing 23. The lug is spaced from the face of the bearing such a dista-nce that when the end of the hub is in contact with the bearing the cam 41 will pass through the space between the lug` and the bearing with just sutlicient clearance to permit its passage. If the shaft 21 should tend to run ahead of the hub 35 the pin 37 will move to the inner end of the helical slot 36 andthus move the hub outwardly and the continued rotation of the shaft will cause the hub to rotate therewith and will thus bring the inclined face of the cam 4l into contact with the lug 42 and the rotary thrust on the shaft will tend to force the cam past the lug and will thus move the hub axially toward the bearing. Inasmuch as the hub is held against rotation with relation to the shaft under these conditions the endwise thrust will also be imparted tothe shaft and the brake member 24 will be forced into firm contact with the brake member 25. The contact of the cam with the lug will tend to check the rotation of the shaft and the seating of the brake member 24 will hold the shaft against further rotation. Should the condition of the brake members be such that they would not control the load when the latter was in movement the load would then be lowered by a series of steps each involving a complete rotation of the shaft 2]. Should the longitudinal movement of the shaft be prevented for any reason, as by the entrance of foreign matter between the two brak-e members the cam 4l will be unable to pass the lug 42 and will therefore form a positive stop which will prevent the shaft from making more than one rotation and will thus positively loch the shaft and the load and prevent the load from dropping.`

ilu

While I have shown and described one' embodiment of my invention I wish it to be understood that I do not desire to be limited to the vdetails thereof as various modifications may occur to a person skilled in the art.

Having now fully described my invention, what I claim as new and desire to secure by Letters Patent, is: y Y Y l. In a lifting jack, y.a lifting element, means for actuating the same to elevate a load, a worm wheel connected with said lifting element for rotation thereby on the downward movement of the load, a worm meshing with said worm wheel, rotatable thereby and A capable of axial movement, a retarding device to normally prevent the rotation of said worm wheel, means to rotate said' worm against the action of said retarding `device and thus permit said worm wheel to be rotated by the load, and means to automatically interrupt the rotation of. said worm by said worm wheel should said retarding device be unable tocontrol the downward movement of the load.

2.- In a lifting jack, a lifting element,means for actuating the same to elevate a load, a worm wheel connected with said lifting element for rotation thereby on the downward movement of the load, a worm meshing with said worm wheel, rotatable thereby and capable of axial movement, a brake member actuated by the axial movement of said worm to hold said worm against rotation, means to relieve the pressure on said brake member and to rotate said worm against the action thereof in a direction to lower the load, and means to automatically check the rotation of said worm by said worm wheel.

3. In a lifting jack, a lifting element,means for actuating thesame to elevate a load, a worm wheel connected with said lifting element for rotation thereby on the downward movement of the load, a worm meshing with said worm wheel, rotatable thereby and capable of axial movement, a brake comprising a movable member which is actuated by the axial movement of said worm to hold said worm against rotation and is capable of rotation with said worm when the latter is rotated in a direction to lower the load, means to relieve the pressure on said movable brake member and to rotate said worm against the action thereof in a direction to lower the load, and means to automatically restore the pressure on said movable brake member when the latter is rotated by said worm. Y

d. In a lifting jack,a lifting element,means for actuating the same to elevate the load, a worm wheel connected with said lifting element for rotation thereby on the downward movement of the load, a worm meshing with said worm wheel, rotatable thereby and ca pable of axial movement, a brake comprising a movable member which is actuated by the axial movement of said worm to hold said worm againstrotatioma crank connected with said worm, means controlled by said crank to reduce the pressure on said movable brake member and to rotate said worm in a direction to lower the load, and means connected with said crank to restore the pressure on said movable brake member when said crank is rotated by said worm.

5. In a lifting aclr, a lifting element, meansfor actuating the same to elevate a load, a worm wheel connected with said lifting element for rotation thereby upon the downward movement of the load, shaft mounted for both rotatory and axial movement, a brake connected with said shaft for operation by the axial movement thereof, a worm carried by said shaft, .meshing with said worm wheel and so arranged that the end thrust imparted thereto by said worm wheel will cause said shaft to exert pressure on said brake, a handle rotatably mounted on said shaft, means controlled by the rotation of said handle on said shaft to impart axial movement to said shaft andreduce the pressure on said brake, and means controlled by the rotation of said handle with said shaft to cause said shaft to be moved in a direction to restore the pres@ sure on said brake. .Y y l 6. ln a lifting jack, a lifting element, means for actuating the same to elevate a load, a worm wheel connected with said lifting element for rotation thereby upon the downward movement of the load, a shaft mounted for both rotatory and axial movement, a brake connected with said shaft for operation by the axial movement thereof, a worm carried by said shaft, meshing with said worm wheel and so arranged that the end thrust imparted thereto by said worm wheel will cause said shaft to exert pressure on said brake, a lowering handle having a hub rotatably mounted on said shaft and provided with a helical slot, a pin carried by said shaft and extending through said slot, said slot being so arranged that the movement of said handle in one direction will impart axial movement to said shaft in a direction to reduce the pressure on said brake, and means to retard the rotation of said handle with said shaft under the influence of the load and thereby cause said shaft to rotate relatively to said hub to be moved axially thereof in a direction to restore the pressure on said brake.

7. In a lifting jack, a lifting element, means for actuating the same to elevate a load, a worm wheel connected with said lifting element for rotation thereby upon the downward movement of the load, a shaft mounted for both rotatory and axialI movement, a brake connected with said shaft for operation by the axial movement thereof, a worm carried by said shaft, meshing with said worm wheel and so arranged that the end thrust imparted thereto by said worm wheel will cause said shaft to exert pressure on said brake, a lower- Cir ing handle comprising a hub rotatably mounted on said shaft and capable of axial movement in one direction from its normal position, said hub having a helical slot, a pin carried by said shaft and extending through said slot, said slot being so arranged that the movement of said handle in one direction will impart axial movement to said shaft and relieve the pressure on said brake. and means to positively move said hub to its normal. position ii said handle should be rotated under the influence ofthe load.

t3. In a lifting jack, a lifting` element, means for actuating the same to elevate a load, a worm wheel connected with said lifting element for rotation thereby upon the downward movement of the load, a shaft mounted for both rotatory and axial movement, a brake connected with said shaft for operation by the axial movement thereof, a worm carried by said shaft, meshing with said worm wheel and so arranged that the end thrust imparted thereto by said worm wheel will cause said shaft to exert pressure on said brake, a lowering handle com prising a huh rotatably mounted on said shaft and capable of axial movement in one direction from its normal position, said huh having helical slot, a pin carried by said shaft and extending through said slot, said slot being so arranged that the movement of said handle in one direction will impart axial n'iovcnient to said shaft and relieve the pressure on said brake, and means to limit the rotation of said handle when said hub is displaced axially from its normal position.

il. In a lifting jack, a lifting element, means for actuating the same to elevate a load, a worm wheel connected with said lifting element for rotation thereby upon the downward movement of the load, a shaft mounted for both rotatory and axial movement, a brake connected with .said shaft for operation ly the axial nlovement thereof, a 'worin carried by said sha ft,inesliing with said worin wheel and so arranged that the end thrust imparted thereto by said worm wheel will cause said shaft to exert pressure on said bra lite, a lowering handle comprising a hub rotatably mounted on said shaft and capable of axial movement with relation thereto, said hub having a helical slot, a pin carried by said shaft and extending through said slot, said slot being so arranged that the movement of said handle in one direction will impart axial movement to said shaft in a direction to reduce the pressure on said brake, a fixed member arranged adjacent to said hub, and a part carried by said hub and arranged to engage said fixed member and impart axial movement to said hub if said handle should be rotated under the influence of the load.

10. In a lifting jack, a lifting element, inea-ns for actuating the same to elevate a load, a worm wheel connected with said lifting element for rotation thereby upon the downward movement of the load, a shaft mounted for both rotatory and axial movement, a brake connected with said shaft for operation by the axial movement thereof, a worm carried by said shaft,meshing with said Worm wheel and so arranged that the end thrust imparted thereto by said worm Wheel will cause said shaft to exert pressure on said brake, a lowering handle comprising a hub rotatably mounted on said shaft and capable of axial movement in one direction from its normal position, said hub having a helical slot, a pin carried by said shaft and extending through said slot, said slot being so ar-` ranged that the movement of said handle in one direction will impart axial movement to said shaft in a direction to reduce the pressure on said brake, a cam carried by said hub, and a xed lug arranged in such a position with relation to said cam that it will be engaged by said cam and will moversaid hub if said handle should be rotated under the influence of the load.

l1. In a lifting jack, a lifting element, means for actuating the same to elevate a load, a worm Wheel connected with said lifting element for rotation thereby on the downward movement of the load, a shaft, a bearing in which said shaft is mounted for both rotatory and axial movement, a brake connected with said shaft for operation by the axial movement thereof, a worm carried by said shaft, meshing with said worm wheel and so arranged that the end thrust imparted thereto by said worm wheel will cause pressure to be exerted on said brake, a lowering handle comprising a hub rotatably mounted on said shaft, capable of axial movement thereon, having' one end arranged to engage said bearing and having a helical slot, a pin carried by said shaft and extending through said slot, a cam carried by said hub, and a fixed member mounted adjacent to said hub and so arranged that said cam will clear the same only when said hub is in engagement with said bearing.

In testimony whereof, I afiix my signature hereto.

ION V. K. HOTT. 

